Join Date: Sep 2008
Location: Victoria B.C. Canada
Thanked 111 Times in 102 Posts
Rep Power: 10
Re: Soler Panel help how many watts?
A 30 watt panel will, with a basic controller which is needed, will only output about 2 amps at best, and that only on the good days. Figure 5 hours a day for useful output - 10 AH a day at best. If you have a group 24 battery it is about 75 - 85 AH. If you take it to 50% SOC you would have to replace say 40 AH. There are inefficiencies in charging - you need to put in about 11 AH for each 10 AH used. So a 30 watt panel will take 4 fully sunny days to recharge from 50%.
I would get a 50 watt panel and a good controller like the Morningstar Sunsaver or similar. That will get you closer to your 2 day goal and be better for the battery as well.
Living aboard in Victoria Harbour